Poster: Temperature Responses
Abs #
179: Structural and functional characterization of plant cold shock domain protein family
In contrast to heat shock response, common mechanism in cold shock response between prokaryotes and eukaryote is largely unknown. Recently, a cold-regulated wheat cDNA that encodes a nucleic acid-binding protein, WCSP1, was identified and found to contain a cold shock domain (CSD) homologous to E. coli cold shock proteins (JBC 277, 35248). The putative WCSP1 protein consists of an N-terminal CSD and three C-terminal CCHC zinc fingers. WCSP1 mRNA and protein levels steadily increases during cold acclimation, respectively. WCSP1 is capable of binding ssDNA/RNA and dsDNA. In the present study, an EST database search was conducted in an effort to identify novel plant sequences that contain cold shock domains (Plant Phys. 131, 12). Highly conserved CSDs were identified within 19 genera that represent lower plants, monocots, dicots and woody plants. Multiple homologues were found within individual species, which is indicative of small gene families. In Arabidopsis, four CSD protein genes were identified in the genome sequence. RT-PCR analysis revealed that three of them are cold-regulated. Of outstanding interest was the discovery that plants also contain complete ORFs that encode putative CSD proteins (Type-II)that are nearly identical to prokaryotic CSPs in size and sequence. It is important to note that the wheat and barley ESTs encode putative proteins solely comprised of a CSD. Furthermore, Type-II ESTs were detected only within wheat and barley and are not within the Arabidopsis genome. Three clones isolated from wheat were able to complement a cold sensitive phenotype of E. coli cspA, cspB, cspE, cspG quadruple mutant. These data suggested a possible involvement of plant CSD proteins in the common mechanisms of cold adaptation in prokaryote and eukaryote.
